A typical mobile communications network architecture comprises a mobile switching centre which is connected to the public switched telephone network (PSTN), the mobile switching centre being connected individually to several base station controllers each of which is connected individually to several base station transceivers. Each base station transceiver is capable of radio communication with mobile communications users within a specific area known as a cell. Cells are normally grouped in clusters and the radio resources allocated to each cell within a cluster are fixed, this is known as fixed channel allocation. In high user density areas cells have a geographically small radio footprint and may be overlaid by a larger umbrella cell which is appropriate for high mobility users. Resources allocated to the umbrella cell are unavailable to the smaller cells which it overlays. In this architecture resource allocation and all the signalling associated with allocating resources is handled centrally by the mobile switching centre.
As demand for mobile communications increases the trend in network architecture is towards employing increased numbers of smaller cells known as micro cells (or pico cells) together with a macro cell with a base station transceiver having a geographically large radio footprint which overlaps the collective radio footprints of the micro cell base station transceivers. This allows low mobility users such as pedestrians to be allocated to micro (or pico) base station transceivers while high mobility vehicular users are allocated to the macrocell base station transceivers. In this case radio resources allocated to individual cells in a cluster are no longer fixed but may be allocated in a dynamic fashion based on allowable levels of interference to surrounding cells, this is known as dynamic channel allocation. This requires measurement of interference levels on the air interface by mobiles and base station transceivers and negotiation for available resources between individual base station transceivers within a cluster. However, this has a number of disadvantages namely:
Because mobile stations contend for resources over the air interfaces there is an increased load on the radio channels due to the dynamic nature of resource allocation and the need to update interference measurements frequently;
Because base station transceivers negotiate for resources in a dynamic fashion this adds significant signalling load to the traditional network architecture.
It is an object of the present invention to provide a mobile communications network which obviates or mitigates the forementioned disadvantages.
It is a further object of at least one embodiment of the present invention to provide a mobile communications network which produces a fast broadcast signalling path between base station transceivers and which does not require use of the air interface.